This invention relates to a magnetic head device suitable for a magnetic recording and reproducing device, the typical example of which is a R-DAT.
In the magnetic head device according to the invention, a coil is not wound on a pair of cores forming a head tip; that is, a bridge core is so arranged that a magnetic flux flows out of one of the pair of cores and flows in the other core, and the coil is placed in the path of the magnetic flux.
FIG. 1 shows the construction of a conventional rotary head device in a magnetic recording and reproducing device such as a video tape recorder or R-DAT.
In FIG. 1, reference numeral 1 designates a shaft which is rotated for instance by an electric motor (not shown), to which a flange 2 is secured; 3, a rotary drum secured to the flange 2 with screws 4 and washers 5; 6, a magnetic head secured to a diaphragm 7 which together with a diaphragm base plate 19 is secured to the rotary drum 3 with a screw 8 and a washer 9; and 10, a screw engaged with the rotary drum. The screw 10 is turned to depress the diaphragm 7 thereby to adjust the level (height) of the head 6. A core 11 having coils 13 and 15 is fixedly secured to the flange 2. A core 12 having coils 14 and 16 is secured to a stationary drum 17 in such a manner as to confront with the core 11. The stationary drum 17 is mounted on the shaft 1, but it is not rotated by the latter 1. The core 11 and the coils 13 and 15 form a rotor, while the core 12 and the coils 14 and 16 form a stator, and the rotor and the stator form a rotary transformer. The head 6 is electrically connected through the diaphragm base plate 19 or a relay base plate 18 to the coil 13 (or 15).
FIG. 2 shows the structure of the magnetic head 6. A pair of cores 21 are juxtaposed in such a manner that one end portion of one of the cores 21 and one end portion of the other core 21 form a gap 22, and the other end portions 23 of the cores 21 are coupled to each other; that is, the cores 21 form a closed magnetic path. A coil 24 connected to the coil 13 (or 15) is wound on the cores 21.
As the shaft 1 is rotated, the head 6, the core 11 and the coils 13 and 15 are rotated as one unit. On the other hand, a magnetic flux from a magnetic tape (not shown) flows in one of the cores 21 through the magnetic gap 22 and flows in the other core 21, and flows out of the latter 21 through the magnetic gap 22. As a result, an electromotive force is induced in the coil 24, and a reproducing signal flows in the coil 13 (or 15). The reproducing signal is applied through the other coil 14 (or 16) forming the rotary transformer to a circuit (not shown).
Another magnetic head (not shown) is provided in such a manner that it is 180.degree. apart from the above-described head 6, and the reproducing output of the head is applied through the coil 15 (or 13) and the coil 16 (or 14) to an external circuit.
In a signal recording operation, the current flows in a direction opposite to the direction of current in the signal reproducing operation.
As was described above, in the conventional magnetic head device, the coil 24 is wound on the cores 21. Therefore, the conventional magnetic head device is manufactured substantially by handwork. Accordingly, the conventional magnetic head device is disadvantageous in that its manufacture takes a relatively long time, and it is accordingly high in manufacturing cost, and it is bulky.
Also as was described above, in the conventional rotary head device, the head 6 is secured to the diaphragm 7, which is secured to the rotary drum 3. Therefore, the conventional device is disadvantageous in that it is large in the number of component, high in manufacturing cost, and bulky.
Accordingly, an object of this invention is provide a magnetic head device which is so designed that it can be manufactured by automation for reduction of the manufacturing cost, and which can be miniaturized.